Abstract

Four simple, sensitive, selective and precise methods were developed for the determination of Ornidazole (OZ) in presence of its degradation product. The first method was based on first derivative spectrophotometry D1 and measuring the peak amplitude of D1 spectra at 290.4 and 332 nm. The second method was depended on measuring the peak amplitude of the first derivative of the ratio spectra DD1 at 288.5 and 328 nm. The third method was the mean centering of the ratio spectra one (MCR), which allowed the determination of OZ in presence of its degradate and the concentration of OZ was determined by measuring the amplitude at 312.8 nm. Separation and determination of OZ by HPLC in the forth method was achieved using Lichrosorb RP-18 column and acetonitrile: water, (50:50v/v), 0.2% triethylamine, the pH was adjusted to 4 using o-phosphoric acid. The flow rate was 1 mL min-1. Beer’s law was obeyed in concentration range 5–30 μg/ml for the first three methods. The linearity range in the forth method was 2-20 μg/ml. The proposed methods were used to determine OZ in its pure powdered form with mean percentage recoveries of 99.86 ± 1.249% and 99.98 ± 0.868% for OZ at 290.4 and 332 nm respectively, in D1
method. In DD1 method, the mean percentage recoveries were 100.11 ± 1.020% and 100.15 ± 1.043% at 288.5 and 328 nm respectively. While in MCR and HPLC methods, the mean percentage recoveries were 100.09 ± 0.387% and 100.00 ± 1.302% respectively. The degradation product was obtained in alkaline stress condition, separated, and identified by LC-MS spectral analysis, from which the degradation product was confirmed. The four methods were validated according to International Conference on Harmonization. The four methods were found to be specific for OZ in presence of up to 80% of its degradation product in the first three methods. The four proposed methods were successfully applied for the determination of OZ in Tibezole® tablets. Statistical comparison between the results obtained by these methods and the reported method for the determination of the drug in its pharmaceutical formulation was done, and it was found that there was no significant difference between them.